[The efficacy of combination chemotherapy of 5'-deoxy-5-fluorouridine (5'-DFUR), cyclophosphamide (CPA) and medroxyprogesterone acetate (MPA) for bone metastasis in breast cancer patients].

5'-DFUR is a pro drug of 5-FU, which is known to be converted by thymidine phosphorylase (dThdPase). A recent pre-clinical study revealed that CPA upregulates dThdPase activity specifically in tumor cells. Furthermore, clinical trials have shown significant response rates in breast cancer patients, when using the chemotherapy combination of 5'-DFUR, CPA and MPA. The purpose of this study was to examine the efficacy of this regimen as a pain reduction therapy for breast cancer patients with bone metastasis. Ten patients who had bone metastasis with restricted ADL were included in the study. All of the patients had had previous exposure to such standard chemotherapy as CAF, CMF, taxol and oral 5-FU administration. The patients were administered daily oral doses of 5'-DFUR at 800-1,200 mg, CPA at 200 mg and MPA at 400-800 mg for two weeks as induction therapy, followed by two weeks rest (one to two cycles). Daily dose of 800 mg of 5'-DFUR, 100 mg of CPA, 400-800 mg of MPA was continuously administered thereafter. The main findings included a significant decrease in pain in eight patients, which continued for more than 6 months. In five patients, the effect lasted more than one year. As the pain decreased, the patients' QOL was improved. Hematological toxicity of more than grade 3 was observed in three patients but only during the induction therapy. One patient had pulmonary thrombosis and required hospitalization. In conclusion, oral administration of 5'-DFUR/CPA/MPA is well tolerated and useful in reducing pain.